Technical Field
The present invention relates to a control circuit for a switching power supply, and more particularly to a control circuit constituted by a semiconductor integrated circuit.
Background Art
In switching power supplies, output voltage is monitored and the associated results are fed back into the system in order to adjust the output voltage obtained from switching. This type of feedback control reduces fluctuations in the output voltage of the switching power supply. Therefore, it is critical to stabilize the operation of the control circuit implementing this feedback control so as to achieve reliable feedback control operation.
One cause of instability in the feedback control operation of a control circuit is short-circuits between terminals of the control circuit. A control circuit is typically constituted by a semiconductor integrated circuit; however, due to limitations in layout efficiency, chip size, and package size of semiconductor integrated circuits, the distance between adjacent terminals is small, and it is difficult to completely avoid short-circuits between adjacent terminals. When a short-circuit occurs between terminals, the control circuit can no longer function normally, and therefore successfully detecting these types of short-circuits between adjacent terminals makes it possible to stabilize the operation of the control circuit. Patent Document 1, for example, describes one such technology for detecting short-circuits between adjacent terminals.